Survey of Energy Resources 2007
Natural Bitument - Resource Quantities and Geographical Distribution
Resource quantities reported here are based upon a detailed review of the literature in conjunction with available databases, and are intended to suggest, rather than to define, the resource volumes that could someday be of commercial interest. Precise quantitative reserves and oil-in-place data on a reservoir basis are seldom available to the public, except in Canada. In cases where in-place resource estimates are not available, the in-place volume has been calculated from an estimate of the recoverable volumes, using assumed recovery factors. For deposits in clastic rocks the in-place volume was calculated as 10 times the original recoverable volumes (cumulative production plus an estimate of the remaining recoverable volume) and for carbonate reservoir accumulations the original oil in place was calculated as 20 times the estimated original recoverable volume. Geologic basin names used in the descriptions are standard and correspond to sedimentary basins shown on the map compiled by St. John, Bally, and Klemme (1984).
A summary of natural bitumen and extra-heavy oil resource quantities is given in Tables 4-1 and 4.2. Natural bitumen is reported in 586 deposits in 22 countries (Table 4-1). It occurs in clastic and carbonate reservoir rocks and commonly in small deposits at, or near, the earth's surface. Natural bitumen accumulations have been mined since antiquity for use as paving materials and sealants. In some places such deposits are extremely large, both in areal extent and in the resources they contain, most notably those in northern Alberta (Fig. 4-1 ), in the Western Canada Sedimentary Basin. The three Alberta oil sands areas, Athabasca, Peace River, and Cold Lake, together contain at least two-thirds of the world's discovered bitumen in place (1.7 trillion barrels) and are at the present the only bitumen deposits that are commercially exploited as sources of synthetic oil. More than one third of the crude oil produced in Canada currently comes from the Alberta natural bitumen deposits.
Outside of Canada, 359 natural bitumen deposits are reported in 21 other countries (Table 4-1). Although Kazakhstan and Russia have the largest amounts of bitumen after Canada, both countries also have large volumes of undeveloped, and undoubtedly less costly, conventional oil. In Kazakhstan, the largest number of bitumen deposits are located in the North Caspian Basin and many of Russia's bitumen deposits are located in the Timan-Pechora and Volga-Ural basins. The North Caspian, Timan-Pechora, and Volga-Ural basins are geologically similar to the Western Canada Sedimentary Basin. Very large resources occur in the basins of the Siberian Platform of Russia (Meyer and Freeman, 2006). Many more deposits are identified worldwide but, as in the case of oil seepages, no resource estimates are reported for them. The volumes of discovered and prospective additional bitumen in place amount to 2 469 billion barrels and 803 billion barrels, respectively.
Extra-heavy oil is recorded in 166 deposits world wide (Table 4-2). Extra-heavy oil deposits are found in 22 countries, with 13 of the deposits being located offshore or partially offshore (Table 4-2). Only one deposit is sufficiently large to have a major supply and economic impact on crude oil markets. That deposit, the Orinoco Oil Belt (Fig. 4-2 ) in the Eastern Venezuela Basin, accounts for about 90% of the discovered plus prospective extra-heavy oil in place, or about 2.2 trillion barrels. In 2005 the upgraded extra-heavy oil produced from this deposit amounted to about 570 thousand b/d, and accounted for almost 20% of the oil production of Venezuela, the world's third leading crude oil exporter. Some of the deposits are separate reservoirs or a single field that consist entirely of extra-heavy oil, whereas other deposits occur as extra-heavy oil reservoirs associated with conventional oil reservoirs in fields known to be primarily conventional. The extra-heavy oil of the Orinoco Oil Belt does not occur with conventional oil reservoirs. Table 4-2 shows in place discovered volume and total in place volumes amounting to 2 294 billion barrels and 2 484 billion barrels, respectively.
In total, Tables 4-1 and 4-2 report a total in-place bitumen volume of 5 756 billion barrels. This volume is slightly less than, but of the same order of magnitude as, the estimated volume of original oil in place in the world's known conventional oil fields. Successful commercial production from the Orinoco Oil Belt and the Alberta bitumen accumulations have proven production strategies and technologies that are likely to be applied to the smaller accumulations represented in Tables 4-1 and 4-2. With the recognition of the commercial potential of these immense resources, additional deposits and volumes are likely to be reported in the future.